Historically high tide causes flooding risks in parts of B.C.
CBC News | Posted: December 27, 2022 10:36 PM | Last Updated: December 28, 2022
Vancouver no longer at risk as tides return to normal for this time of year
The peak of a so-called king tide has passed without major damage in Vancouver, as flood watches and high streamflow advisories remain posted across Vancouver Island and much of B.C.'s inner south coast.
The big tide combined with heavy rain and snowmelt had raised the risk of flooding after pre-Christmas snowstorms.
Environment Canada said the tide pushed water levels at Point Atkinson in West Vancouver to a height of 5.70 metres, breaking the previous record of 5.61 metres set in 1982.
High tides combined with a storm surge — caused by a low pressure weather system — have affected B.C.'s south coast and the coast of Washington, said Jimmy Zammar, director of urban watersheds, sewers and drainage for the City of Vancouver.
"Combined together, we're looking at water levels that are higher than we have seen in recent decades," he said, noting the city avoided flooding when the tides peaked around 9:30 a.m. PT. "We were looking at 5.55 metres of water levels, which ends up being two-and-a-half metres above the average sea level."
The City of Vancouver had warned Monday of elevated flood risk as so-called king tides — extremely high tides that happen about twice a year when the sun and moon's gravitational forces reinforce each other — were due early Tuesday at the same time as strong winds were forecast to cause a significant storm surge.
Main tidal threat has passed for Vancouver
However, the main threat had passed for Vancouver and area by Tuesday morning, and normal winter weather with a cycle of high and low tides had resumed, Zammar said.
"Usually, the things that we look out for are flooding at the coastline or impacts inland into streets right of way or private property and what may be cascading impacts from that," he said. "Thankfully, we're not facing that today."
The River Forecast Centre has issued flood watches for Metro Vancouver, the Fraser Valley, Howe Sound and the southern two-thirds of Vancouver Island as heavy rain drenched the regions on Sunday and Monday, speeding snowmelt and causing additional run-off.
Environment Canada is calling for 60 to 120 millimetres of rain across the Sunshine Coast and Metro Vancouver by Wednesday morning.
The weather office said it has "high confidence'' that the rain and snowmelt, coupled with strong winds and high tides, will cause potentially damaging coastal flooding on low-lying areas from Vancouver and Howe Sound to the Sunshine Coast, East Vancouver Island and southern Gulf Islands.
The River Forecast Centre also said officials are keeping a close eye on the situation in northwest Washington state where a flood watch is in effect as the Nooksack River threatens to top its banks.
High water on that river was linked to last November's devastating floods in the Fraser Valley and the centre said there may be a "small chance of a minor overflow'' into the Sumas River drainage on the B.C. side of the border.
City crews concerned about drainage system
Amir Taleghani, senior flood and drainage planning engineer with the City of Vancouver, said the flooding event last year was particularly influenced by the wind, but that is not the case this year.
"Today, the wind is in a direction that's not causing us as much trouble as last year," he said.
He said crews have been working overnight in multiple locations as the high storm surge in connection with one of the highest tides of the year raised concerns about the performance of drainage systems.
"You're having rainfall happening at the same time as these very high coastal water levels. So that water has to go somewhere and that's where our drainage system infrastructure comes into play."
The City of Vancouver had warned Monday of elevated flood risk as so-called king tides — extremely high tides that happen about twice a year when the sun and moon's gravitational forces reinforce each other — were due early Tuesday at the same time as strong winds were forecast to cause a significant storm surge.
"Low-lying areas will be at an elevated flood risk and may experience overland flooding,'' the City of Vancouver said in a statement.
Part of the Stanley Park seawall from the Lions Gate Bridge to English Bay and in front of Kits Pool remain closed as a precaution.
Winter storm warnings remain for Interior
Residents are strongly advised to monitor outdoor conditions in flood-risk areas and make travel plans accordingly for their safety, the city said.
Zammar also recommended residents download the Alertable app on their phones to receive weather alerts from the city.
Elsewhere, Environment Canada maintained winter storm warnings for parts of the southern and southeastern Interior as 25 to 30 centimetres of snow was forecast in the Kootenay and Boundary area before changing to rain or freezing rain later in the day.
In response to an extreme weather alert, with temperatures that feel at or below 0 C, the City of Vancouver has opened additional shelter spaces and warming centres from Dec. 27-29.
A travel advisory was posted urging drivers to stay off Highway 3 east of Osoyoos.
The route remained open, although DriveBC, the province's online travel advisory system, warned of the "high probability'' of closures on short notice. The highway is expected to close at Kootenay Pass from 8 p.m. to 2 a.m. PT for avalanche control work.
Highway 1 through the Fraser Canyon just north of Hope reopened Tuesday afternoon, after being shut on Monday because of an avalanche hazard.